Electric heater



FIG. 1 is a front and right side perspective view of an electric heater, showing my new design;

FIG. 2 is a front view thereof;

FIG. 3 is a rear view thereof;

FIG. 4 is a left side view thereof;

FIG. 5 is a right side view thereof;

FIG. 6 is a top view thereof; and,

FIG. 7 is a bottom view thereof.

The structural features depicted by broken lines in FIG. 2, FIG. 3 and FIG. 7 have been shown for the purpose of illustrating portions of the electric heater that form no part of the claimed design. 

CLAIM I claim the ornamental design for an electric heater, as shown and described. 